Om foreleseren
Frode Jacobsen's presentation:
I earned my first Bachelor degree in Forestry from the regional college of North-Trondelag in 1997, my second Bachelor degree in Biology from the University of Oslo in 2002, a Master's degree in Biology from UoO in 2004 based on my study of population genetics of Scandinavian Peregrine Falcons under the mentorship of Dr. Jan Lifjeld, and recently earned a Ph.D. from the University of Maryland, Baltimore County in 2011 based on my studies of multilocus phylogeny and population genetics of New World orioles under the mentorship of Dr.Kevin Omland. Currently, I am a postdoc in Dr. Kevin Omland's lab continuing my work on orioles, omparing different classes of species tree methods and examining the effects of gene flow on phylogenetic
inference.
Abstract
Mitochondrial DNA (mtDNA) has demonstrated great utility for phylogeography and phylogenetics, but has several limitations and must be corroborated by independent nuclear evidence. Stochastic lineage sorting and introgressive hybridization frequently cause gene genealogies to be incongruent with the species tree and can render even the most strongly supported gene tree misleading. Here, I use multiple nuclear introns and several multilocus approaches to infer the evolutionary history of a large genus of closely related orioles. Concatenation of six Z chromosome introns yielded a well-resolved nuclear phylogeny that corroborated many nodes supported by mtDNA, especially deeper in the oriole tree. Species tree analysis of seven unlinked introns and multiple individuals per species further supported many of these congruent nodes but also revealed strong conflict between mitochondrial and nuclear DNA regarding relationships within the “northern oriole” group. The mtDNA gene tree supported a controversial sister relationship between black-backed oriole and Baltimore oriole, whereas our nuclear species tree supports the traditional taxonomy of black-backed oriole sister to Bullock’s oriole. This conflict most likely arose following historical mitochondrial introgression and replacement in black-backed oriole, causing the mtDNA tree to be misleading. Extensive nuclear introgression between Baltimore oriole and black-backed revealed by Isolation-with-Migration (IM) analysis provide additional evidence of historical or ongoing gene flow between these orioles. Increased documentation of introgression in nature stresses the need for novel methods that account for gene flow when inferring the evolutionary history of closely-related species.